class seventh

Chapter no 5


1, Fill in the blanks:


(i) A neuron is a long thread like structure.

(ii) The Central nervous system consists of brain and spinal cord.

(iii) Our Tongue can detect all kind of tastes.

(iv) The place where one bone is connected to another bone is called a joint
.
2 Tick (√) True or False:

(i) The heart beat is under our direct control. (x)
(ii) At movable joints bones are held together by strong tissue called ligaments. (√)
(iii) Skeletal muscles enable the skeleton to move. (√)
(iv) Cardiac muscles are found in heart. (√)
(v) Hind brain consists of cerebellum and medulla oblongata. (√)
(vi) The movement of a message along a nerve is always a two ways path. (√)

3 Encircle correct answer from the following choices:

(i) In human female fertilization takes place in:
(a) Ovary (b) Ovule
(c) Oviduct (√) (d) Ovum
(ii) Usually in how many days one egg is released from an ovary of a
mature human female.
(a) 27 days (b) 28 days (√)
(c) 29 days (d) 30 days
(iii) Human being can hear high pitched sound up to this cycle.
(a) 18,000 cycles (b) 19,000 cycles
(c) 20,000 cycles (√) (d) 21,000 cycles

(iv) Ear is the organ.
(a) Hearing (b) balance
(c) Hearing and balance (√) (d) sight
(v) Human eyes can detect only.
(a) Blue light (b) ultraviolet
(c) Infrared (d) white light (√)
4 Write short answers:
i) What are the functions of skeleton?
Answer: Some functions are given below
(i) Support and function (Gives body support and proper posturing)
(ii) Protection (for soft body parts)
(iii) Movement (it is due to skeletal framework)
ii) Define :(a) joint (b) ligament (c) neuron
Answer: Joint:
It is the place the two bones are connected.
Ligament:
At movable joints, bones are held on place by strong tissue
called ligament.
Neuron:
It is the structural and functional unit of nervous system.
iii) Name three main types of bones.
Answer: I (Long bones)
2 (Flat bones)
3 (Small bones)
4 (Irregular bones)
iv) Name the types of muscles.
Answer: I (Smooth muscles)
2 (Skeletal muscles)
3 (Cardiac muscles)
v) How transmission of message take place in the nerve cells.
Answer: Sensory neurons:
Carry nerve impulse or massages from sense organs to
the brain and spinal cord.
Motor neuron:
Carry nerve impulses or massages from brain and spinal cord
to the muscles or glands (As reply action)
Note:
Associative neuron:
Connects the sensory to the motor neurons.
vi) Name the sense organs in man.
Answer: Names of sense organs are given below.
(i) Nose
(ii) Tongue
(iii) Skin
(iv) Eyes
(v) Ears
5) Describe the four types of bones in man.
Answer:
The four types of bones are given below.
i) Long bones:
Our legs, arms and chest consist of long bones. They have
hollow cavity, filled with bone narrow.
ii) Flat bones:
They posses no hollow cavity .They are present in skull
and shoulders.
iii) Small bones:
Present in wrist and ankles.
iv) Irregular bones:
These bones are of irregular shapes, Vertebrae and hip-bones
are example.
6) Write the functions of skeleton.
Answer: Some of the prominent functions of skeleton are given below.
i) Support and shape:
. It helps and supports the body to get proper posture.
ii) Protection:
It is provided to the delicate body organs /parts especially
to the heart, lungs, liver, and brain
iii) Movement:
The muscular net is not enough to cause movement but along
with skeletal framework movement is produced
iv) Calcium deposit:
Calcium and phosphorus is deposited here in bones.
v) Blood cell genesis:
Red blood cells are made in bone marrow
7) Describe the types of joints .Define joint.
Answer: Joint:
The place where one bone is attached / connected to another bone is
called a joint.
Skeleton has several kinds of movable joints:
i) Ball and socket joint:
(a) Presence: Joint at hip and shoulder.
(b) Quality: Allows movement of arms and legs in almost any
direction even in circle.
ii) Hinge joints:
(a) Presence: Joint in the fingers and knees.
(b) Quality: Allows movement of fingers back and fourth.
Note: The elbow has two joints.

(a)Hinge joint: Allows movement of arm.
(b)Pivot joint: Helps to move palm up or down.
iii) Sliding joint:
It enables the movement of the ankle and wrist in any direction.
8) Describe the types of muscles in man.
Answer: Muscles:
There are about 600 muscles.
Types of muscles: There are about three types of muscles.
Skeletal muscles:
They are directly under the control of man and are attached to
the skeleton.
Smooth muscles:
They are not directly under the control of man.
E.g. blood vessels, internal organs like stomach.
Cardiac muscles:
Muscles associated with the heart are called cardiac muscles.
9) Draw and label neuron.
Answer: See fig 5.4 –page at page 44
10) Describe a human brain.
Answer: Location:
It is enclosed in a strong bony skull called the cranium.
Divisions:
It has three main parts.
(1) Fore brain.
(i)Cerebrum: it is the largest part of the brain.
(a)External morphology (surface) Surface is wrinkled
and folded.
(b)Functions: Movement, Reasoning, Speech.
(ii) Mid brain. (Next-under the cerebrum)
(a) Functions: Eye, Ear.
(iii) Hind brain.
Included (Cerebellum, Medulla oblongata)
(a) Cerebellum:
Location: Behind the midbrain.
Function: Posture, Balance, Co-ordinates movement.
(b) Medulla oblongata: It connects the brain and the
Spinal cord.
Function: Controls Respiration, Digestion, Heart beat rate.

11) Write notes on: (i) Ear (ii) Eye (iii) Sense of taste.
Answer :( i) Ear:
Ear is the organ of hearing and balance. The ear consists of three
parts i-e an outer ear, middle ear, inner ear .The outer ear directs sound waves into the middle ear. The inner ear has a membrane and three small soft bones. These three bones are connected to one another. A tube also connects the middle ear to the pharynx. By movement of air in the tube, air pressure inside the middle air can be adjusted. The inner air consists of a cavity containing a fluid, and membranous structure which is connected to the brain by an auditory nerve. The sound waves from the external-middle ear reach the inner ear. Then the impulse is sent to a special region in the brain. Thus the brain becomes able to determine the sound.

(ii) Eye:
The eye is the sense organ of sight. Light from an external object enters the eyes. Passing through lens of the eyes it falls on the last inner membrane (retina) of the eye, forms a real image which is upside down and smaller than the object. The optic nerve of eyes then sends message to the brain. The message is interpreted by the brain cells which invert the image. Then an upright object is seen.
Eyes can detect the sunlight as white light. Eyes cannot detect the ultra violet and infra red light. The common defects of eyes are short sightedness, long-sightedness which are due to excessive eye strain and old age and can be improved by using lens. Another eye disease is called cataract in which lens become opaque. It is cured by lens transplant.

(iii) Sense of taste:
The lower surface of the tongue is smooth while the upper surface is rough due to he presence of taste buds. The tip of the tongue is most sensitive to sweet foods, the sides of the tongue to sour and salty foods, and the back of the fungus sense the texture of food and its temperature.

12) Describe human male and female reproductive system.
Answer (i) Male reproductive System:
Sexual reproductive organs in man are the two testes. Testes are enclosed in a loose bag of skin. The testes produce sperm cell. A tube runs from each testis. These tubes connect with a larger tube through which sperms pass out of the body of the male during adulthood.
(ii) Female reproductive System:
In females, egg cells develop in reproductive organ called ovaries. Usually one egg is released from an ovary of a mature human female about every 28 days. When an Egg is released from an ovary, it is drawn into a tube called oviduct. During this time in the oviduct, the egg cell can be fertilized, if the sperms are released in the female body.The fertilize egg or zygote travels down the oviduct and eventually becomes attached to the wall of the uterus, which is a muscular organ where development is completed. If the egg is not fertilized, it passes out of the female body.
13) Label the following diagram:
Answer See fig 5.9 on page 47.
































Chapter no 6


1, Fill in the blanks:
(i) Living things and non living things make the environment.

(ii) Organisms along with their environment form an ecosystem.

(iii) To maintain an ecosystem energy is required.

(iv) Atmosphere in motion is called wind.

2 Tick (√) True or False:

(i) A fire of few minutes can greatly change in an ecosystem. (x)
(ii) Green plants are producer. (√)
(iii) Animals are consumers. (√)
(iv) A food chain shows how energy is passed from one organism to another. (√)

3 Encircle correct answer from the following choices:

(i) Life exists only on this planet:
(a) Jupiter (b) mars
(c) Moon (d) Earth (√)
(ii) It is an ecosystem:
(a) Pond (b) forest
(c) Desert (d) all of them. (√)
(iii) The material that comes from the environment is:
(a) Natural resources (√) (b) non-renewable resources
(c) Cycles (d) renewable resources
4 Write short answers:
i) Define: (a) environment (b) ecosystem
(c) Food chain (d) food web
(e) Conservation
(a) Environment: It is the surroundings in which an organisms lives.
(b) Ecosystem: It includes group of communities and their
non-living environment.
(c) Food chain: The flow of energy from producers to consumers in
a community.
(d) Food web: A diagram that shows overlapping relationship of many
food chains.
(e) Conservation: To safe guard the natural resources.
ii) Name the physical factors of the ecosystem.
Answer: Physical factors of the environment are energy, temperature, water,
Air, fire, gravity, topography.
iii) Name the renewable and non-renewable resources of the environment.
Answer: Renewable:
Plants, animals, water, soil, metals, and oils are all examples of natural resources . Some natural resources are renewable.
Non- Renewable:
Minerals, metals, coal, oil, and natural gas are example of non-renewable resources.
5. Describes physical factors of ecosystem.
Answer: Energy is required to maintain an ecosystem. The sun is the main source of energy. Light energy from the sun is used by green plants to make food. On this food all other animal life exists. There is an increase in temperature with the absorption of energy from the sun by non-living things. Heat energy flows from flows from warmer to the cooler part of the environment.
The abundance of water or the lack of it has a great effect on the ecosystem of a given region. The atmosphere is a store house of some very important substances needed by living things, e.g., carbon dioxide, nitrogen, oxygen. Atmosphere in motion is wind. These air currents redistribute the components of the atmosphere. A fire of a few minute duration can greatly change an ecosystem. There are adaptations in plants and animals to overcome the pull of gravity. Topography (external features of the Earth) of the Earth also determines the type of organism that can exist in a particular place.
6. Describes the biological factors of ecosystem.
Answer: Green plants make food, so they are called producers. Animals are consumers. Herbivores are the primary consumers. The camivores may be the secondary and tertiary consumers. When animals die they become food for bacteria and fungi, which are the decomposers. Decomposers work also on plants.
7. What is food chain? Explain.
Answer: In a community, a caterpillar is a herbivore. As the caterpillar moves it eats leaves. Suddenly the caterpillar is captured by a bird. The young bird becomes careless. Suddenly it is in the grasp of an eagle (see fig. 6.1). Eventually, the eagle dies and decays. December use the eagle for their meal. The chain of evens described can be shown in a food chain. A food chain shows how energy is passed from one organism to another.
8. What is food web? Explain.
Answer: A snake may also eat a lizard or a frog. An owl may feed directly on a mouse. In addition, some animals are omnivores. All the possible feeding relationships and altered food chains in an ecosystem make up a food web.
9. Describes food pyramid.
Answer: A food chain is necessary so that all organisms can obtain their share of the energy entering the ecosystem. However much energy is lost between each link of a food chain. There is more energy in the produces. The herbivore gets loess energy from the plant than the stored energy in the plants. Likewise primary and secondary consumers get less energy. Thus each link in the food chain has less potential energy available to it than the previous link. This explains why one kind of organisms feeds upon specific organisms. It would make little sense for a lion to prey upon small rats. The lion would expend more energy in catching a rat than he would obtain by eating it. Instead it is better for a lion to hunt and eat a single zebra or deer. A food chain rarely includes more than four links. So much energy is lost in a food chain that not enough energy remains to support fourth fifth order consumers. So at the start of a chain the number of producer is more. The number of primary consumer is less than they produce. Likewise the number of secondary consumers is less than the primary consumer. For example there are more mice than there are snakes which feed upon mice. This relationship is known as food pyramid or pyramid of numbers.
10. Describes balance and imbalance in nature.
Answer: Plants and animals used these materials and did not return them to the ecosystem; they would have been used up a long time ago. Instead, organisms use these non-living materials over and over again due to recycling.
Adding any substance to the environments in harmful amount is called pollution. Any substance that causes pollution is a pollutant. Pollution is a serious problem because it causes imbalance in the environment. For example pollution of water air, loin of an area will have harmful effects on the life of plants and animals.




1. Fill in the blanks:
The thread like structure found in nucleus is called chromosome.
i) The unit of heredity is gene.
ii) Genes are presents on chromosome.
iii) The activities of the cell are controlled by nucleus.
2. Write short answers:
i) Define: trait, heredity, genetics, nucleotide, nucleus, and chromosome.
Answer: Trait:
Trait are characteristics, such as leaf shape, color of flower, eye color, etc. that are passed from parents to offspring’s.
Heredity:
Passing of traits or characteristics from one generation to
the next is called heredity.
Genetics:
The science of heredity is called genetics.
Nucleotide:
Nucleotide is a building block of DNA. It consists of Phosphate, sugar, base. There are four types of bases. That is Adenine, Thymine, Cytosine and Guanine.
Nucleus:
It is the largest organelle of the cell.
It is surrounded by nuclear membrane.
It controls all the activities of the cell.
Chromosome:
The thread like structures in the nucleus is the chromosomes. A typical chromosome consists of two chromatids which are joined together by Centromere.
ii) What are the components of DNA?
Answer: DNA is a very large molecule consists of units called nucleotides. A
molecule of DNA consists of two strands linked with each other by bands like ladder twisted around each other.
iii) What is a gene?
Answer: Gene is a unit of inheritance.
3. Describe the structure and function of nucleus.
Answer: It is the largest organelle of the cell. It is surrounded by nuclear
membrane. It controls all the activities of the cell. It is circular or oval in shape. Its fluid is called nueleoplasm. It contains a network of fine chromatin threads. When the cell prepares to divide the fine chromatin threads become visible as chromosomes.
.
4. Describe the structure of chromosome.
Answer: A typical chromosome consists of two chromatids. The two chromatids
are attached to the same centromere. The centromere divides the chromosomes into the equal or unequal arms. According to the position of centromere chromosomes may be rod shaped, J-shaped and V shaped.
5. Write brief notes on
(a) Centromere (b) Homologous chromosomes
Answer:
Centromere:
The point at which the chromatids are attached is called
Centromere.
Homologous chromosomes:
Chromosomes occur in pairs. Same type of chromosomes is called homologous chromosomes.


Chapter 8
Q.1. Fill in the Blanks
(i) The electrons, protons and neutrons are the fundamental particle present in Nucleus
(ii) Rutherford proposed that an atom consists of parts.
(iii) The mass of an atom is sum of proton and Neutrons.
(iv) K shell can have maximum 2 electrons.
(v) The atoms of an element which have same atomic number but different atomic mass are called isotopes.
(vi) The valiancy of lithium is +1
(vii) When an atom has 10 electrons and 10 protons its atomic number is 10
(viii) Chlorine has 2 isotopes.
(ix) The atomic mass is represented by A
(x) The isotopes of an element have different physical properties but same chemical properties.

Q.2. Tick (√) true of false.
(i) Helium atom has two protons in its nucleus. √ True / False
(ii) All isotopes of hydrogen consists of only one proton in the nucleus √ True / False
(iii) K shell has the lowest energy. √ True / False
(iv) The number of electrons in K and L shell are always same True / False √
(v) The atom of hydrogen is heavy then and atom of lithium True / False √
(vi) An atom is the smallest particle of an element. √ True / False

Q. 3. Encircle the correct answer from the following choice.
(i) An atom of carbon contains number of protons.
a. 2
b. 4
c.
6
d. 8
(ii) The valency of hydrogen is
a.
1
b. 2
c. 3
d. Zero
(iii) Atoms of an element are
a.
Identical
b. Different
c. Dissimilar
d. Non Identical
(iv) The total number of protons and neutrons present in the nucleus of an atom is called.
a.
Atomic number
b. Atomic mass
c. Atomic Proton
d. Atomic Neutron
(v) An isotope of chlorine Cl37 has number of neutrons
a. 17
b. 18
c.
20
d. 22
(vi) The number of electrons in ‘L’ shell of carbon atom are
a.
2
b. 4
c. 6
d. Zero

Q.4: Differentiate between atomic mass and atomic number.
Ans:
In case of atomic number we consider only the number of protons inside the nucleus, while in case of atomic mass we consider both the number of proton as well as number of neutrons. Present inside the nucleus.

Q.5. Define isotopes and describe the isotopes of hydrogen.
Ans:
Isotopes:
Atoms having same atomic number but different mass number are called isotopes.
Isotopes of Hydrogen:
Hydrogen element passes 3 isotopes
Protiun: It is also called ordinary hydrogen. It has one proton and no neutron, represented by 1H1 or H.
Deutrium: Also known as heavy hydrogen. It has one proton and one neutron, represented as 2H1 or D.
Tritium: it exist rarely, in traces, it has one proton 2 neutron, represented 3H1 or T.

Q.6. Define valency and explain the distribution of electrons of an atom.
Ans:
The combining capacity of an element is called valency.
Distribution of electrons of an atom.
Capacity of electron in various shells
Shell Number
Name of Shell
Capacity of Electrons
1st
K
2
2nd
L
8
3rd
M
18
4th
N
32

Q.7. Calculate the number of protons, neutrons and electrons in the following atoms.
(a) 1H1 (b) 7Li3 (c) 10B5
Ans:
(a) 1H1
Number of protons =1
Number of Electrons = 1
Number of Neutron = 0

(b) 7Li3
Number of Protons =3
Number of Electrons = 3
Number of Neutron = 4

(c) 10B5
Number of Protons =5
Number of Electrons =5
Number of Neutron = 5

Q. 8. Draw the electronic configuration of following atoms.
(i) Carbon (ii) Oxygen (iii) Neon
Ans:

(i) Carbon:












(ii) Oxygen













(iii) Neon







Chapter 9
Q.1. Fill in the blanks.
(i) An atom can’t exist free and take part in a chemical reaction.
(ii) A molecule of hydrogen consist of 2 atoms of hydrogen.
(iii) Gold is costly metal.
(iv) In the earth’s crust the most abundant element is Oxygen.
(v) Metals exist mostly in solid state.
(vi) There are 92 naturally occurring elements.
(vii) Water is made up of two elements hydrogen and oxygen.
(viii) Metals are used to form Metallic goods.
(ix) The hardest naturally occurring substance is Diamonds.
(x) Sulphuric acid is prepared from sulphur.

Q.2. Tick (√) true of false.
(i) Metals are brittle. True / False √
(ii) Metal are softer and non-metals are harder. True / False √
(iii) Copper metal is a good conductor of electricity. √ True / False
(iv) Iron is used in the manufacturing of aero planes. True / False √
(v) Graphite is used for cutting glass. True / False √

Q. 3. Encircle the correct answer from the following choice.
(i) The most abundant metal in the earth’s crust is
a. Iron
b. Aluminium
c.
Oxygen
d. Calcium
(ii)
Which of the following metal exist in liquid state
a. Mercury
b. Zinc
c. Bromine
d. Copper
(iii) Which of the following exist in liquid state?
a.
Chlorine
b. Bromine
c. Iodine
d. Neon
(iv) The nature of most abundant element in the earth’s crust is
a.
Metal
b. Non Metal
c. Metalloid
d. None of these
(v) Which of the following is brittle
a. Sodium
b. Magnesium
c. Sulphur
d.
Copper
(vi) Which of the following is used for vulcanization of rubber.
a. Nitrogen
b. Phosphorus
c.
Oxygen
d. Sulphur
(vii) Which of the metal is used for making radiation shield again X-Rays.
a. Zinc
b.
Copper
c. Lead
d. Aluminium

Q.4. Differentiate between atom and molecule with examples.

Sr. No
Atom
Molecule
1
Atom is the smallest particle of an element. Which may or may not exist independently like C, He.
Molecule is the smallest independent particle of an element or a compound.
e.g. H2, H2O.
2.
It is uninulear.
It is usually compound of two nuclei, sometimes Polly nuclear.

Q.5. What are metalloids?
Ans:
They are also called as semi metals. The exhibit both the properties of metal and non metal at the same time. For example Boron, Silicon, Arsenic, antimony.

Q.6. Differentiate between metals and non metals.

Sr. No
Metals
Non Metals
1
They are Shiny
The do not pass shine except Iodine and Diamond
2.
The conduct heat, electricity
The do not conduct heat & Electricity
3.
They are hard, only gallium and mercury are in liquid shape.
Some of them are gases, some are liquid. E.g. bromine as liquid phosphorous as solid and chlorine as gas.
4.
Posse’s high density.
Posses low density.
5.
They are ductile and malleable
The are not
6.
Metals have tensile strength
The are brittle
7.
They have high melting point
They posses low

Q.7. Find out which of the following are metals, non metals and metalloids.
i. Hydrogen ii. Oxygen iii. Sodium iv. Carbon v. Lead
vi. Copper vii. Silicon viii. Iron ix. Calcium x. Boron
Ans:

Metal
Non Metal
Metalloids
Sodium
Hydrogen
Silicon
Lead
Oxygen
Boron
Copper
Carbon

Iron


Calcium




Q.8. Write down the use of
i. Carbon ii. Nitrogen iii. Lead
Ans:
i. Carbon
It is an important non-metal. It exists as diamond, graphite, bucky balls, and as carbon black, charcoal, coal, coke etc. Each of them is important on its own place.
Diamond: It is precious one
Graphite: Use as electrodes
Carbon black: Used in making rubber tyres, black shoe polish, printers ink, typewriting
Ribbons, carbon paper etc.
Coal and Coke: Used as fuel
Charcoal: Used as absorbent for removing color in sugar industry.

ii. Nitrogen
(i) Fertilizers are made
(ii) Nitric acid and ammonium is made
(iii) Used in electric bulbs and transistors.

i. Lead
(i) Used in making batteries
(ii) Used in making bullets.
(iii) Used in making shield against radio active radiation.